Photographic products and processes



United States Patent "ice 3,239,337 PHGTOGRAPHIC PRODUCTS AND PROCESSES Howard C. Haas, Arlington, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware N0 Drawing. Filed Nov. 25, 1960, Ser. No. 71,424 7 Claims. (Cl. 9629) This invention relates to photography and more particularly to novel photographic products and processes.

One object of this invention is to provide novel imagereceiving elements for use in color diffusion transfer processes.

Another object of this invention is to provide novel color diffusion transfer processes utilizing said imagereceiving elements.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure,

and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

The present invention is particularly related to color diffusion transfer processes. In such processes a sheet of photosensitive material is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, an imagewise distribution of color-providing materials is formed. At least a portion of these color-providing materials is transferred by means of an alkaline aqueous processing liquid to a superposed image-receiving layer to form a colored positive image thereon. As examples of such processes, mention may be made of the processes claimed and disclosed in US. Patent No. 2,983,606, wherein dye developers (i.e., dyes containing a silver halide developing function and capable of developing exposed silver halide) are the color providing materials; the processes claimed and disclosed in US. Patent No. 2,647,049, issued July 28, 1953, to Edwin H. Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing materials; and the processes disclosed in US. Patent No. 2,774,668, issued December 18, 195 6, to Howard G. Rogers, wherein complete, preformed dyes which are capable of coupling are used as the colorproviding substances.

The image-receiving elements used in such processes generally comprise an opaque or transparent support coated with an image-receiving layer of a dyeable material which is permeable to the alkaline aqueous processing solution. In the past, it has been proposed to use filmforming materials such as polyvinyl alcohol and nylons such as N-methoxy-methyl polyhexamethylene adi amide as the dyeable materials.

It has now been discovered that by using an image-receiving layer comprising a partial acetal of polyvinyl alcohol and a trialkylammonium benzaldehyde quaternary salt, i.e., a partial acetal prepared from polyvinyl alcohol and a trialkylammonium benzaldehyde quaternary salt,

Patented Mar. 8, 1966 transfer images having good stability and improved density may be obtained. Especially good results have been obtained using those acetals in which the trialkylammonium substituent comprise-s not more than 8 carbon atoms. Segments of such acetal polymers may be illustrated, for example, by the following formula:

wherein X is an acid anion and each R is an alkyl group; said Rs together comprising not more than 8 carbon atoms.

The image-receiving elements of this invention have been found to be particularly useful in color diffusion transfer processes which employ dye developers. The improvements have been especially marked when azo and anthraquinone dye developers are employed. Dye developers, as noted above, are compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function. They may be further defined as dyes which are silver halide developers. By a silver halide developing function is meant a radical capable of developing an exposed silver halide image. Particularly useful dye developers are those in which the silver halide developing function is provided by the presence of a benzenoid developing radical. A preferred benzenoid developing radical in such compounds is a hydroquinonyl radical. Examples of representative dye developers are given in previously mentioned US. Patent No. 2,983,606. Additional useful dye developers are described in the following copending US. applications:

Application Serial No. 612,045, filed September 25, 1956, in the names of Elkan R. Blout, Milton Green and Howard G. Rogers (now abandoned and the subject matter of which is incorporated in continuation-in-part application Serial No. 144,816, filed October 18, 1961, now US. Patent No. 3,134,672, issued May 26, 1964).

Application Serial No. 612,052, filed September 25, 1956, in the names of Milton Green and Howard G. Rogers (now abandoned).

Application Serial No. 612,053, filed September 25, 1956, in the name of Myron S. Simon (now abandoned and the subject matter of which is incorporated in continuation-in-part application Serial No. 196,523, filed May 21, 1962, now US. Patent No. 3,183,089, issued May 11, 1965).

Application Serial No. 612,054, filed September 25, 1956, in the names of Helen P. Husek and Myron S. Simon (now abandoned and the subject matter of which is incorporated in continuation-in-part application Serial No. 197,283, filed May 24, 1962).

Application Serial No. 612,055, filed September 25, 1956, in the name of Helen P. Husek (now abandoned and the subject matter of which is incorporated in continuation-in-part application Serial No. 192,355, filed May 4, 1962, and continuation-impart Serial No. 192,354, filed May 4, 1962, now US. Patent No. 3,134,672, issued May 26, 1964).

Application Serial No. 755,804, filed August 18, 1958, in the names of Elkan R. Blout, Saul G. Cohen, Milten Green and Myron 8. Simon (now abandoned).

Application Serial No. 824,785, filed July 3, 1959, in the names of Elkan R. Blout, Marilyn R. Cohler, Milton Green, Myron S. Simon and Robert B. Woodward -(now abandoned and the subject matter of which is incorporated in continuation-in-part application Serial No. 233,461, filed October 26, 1962, now US. Patent No. 3,135,606, issued June 2, 1964).

Application Serial No. 849,727, filed October 30, 1959, in the names of Elkan R. Blout and Myron S. Simon (now abandoned).

Applications Serial Nos. 1,442 and 1,443, both filed January 11, 1960, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. Woodward.

In color diffusion transfer processes employing dye developers, a latent silver halide image in a photosensitive element is developed in the presence of the dye developer and, as a result of this development, the dye developer in the exposed areas is oxidized and substantially immobilized. At least a portion of the immobilization is believed to be at least due, in part, to a change in the solubility characteristics of the dye developer upon oxidation and especially as regards its solubility in alkaline solutions. In unexposed and partially exposed areas of the emulsion, the dye developer is unreacted and dilfusible, and thus provides an imagewise distribution of unoxidized dye developer, dissolved in the liquid processing composition, as a function of the point-to-point degree of exposure of the silver halide emulsion. At least part of this image wise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise diffusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide a reversed or positive color image of the developed image.

The acetals for use in this invention may be prepared by known methods. In general, they may be prepared by condensing a trialkylammonium benzaldehyde quaternary salt with polyvinyl alcohol. The polyvinyl alcohols for use in the synthesis may be selected from the various polyvinyl alcohols which are commercially available. As examples of suitable polyvinyl alcohols, mention may be made of Elvanol 72-60 (trade name of E. I. du Pont de Nemours & Co., Wilmington, Delaware), and Gelvatol 1-75 (trade name of Shawinigan Products Corp, New York, N.Y.). Usually, the degree of acetalization can be varied over a. considerable range. Generally, the water sensitivity of the acetals and especially of the acetals wherein the trialkyl substituents are lower alkyls, e.g., methyl, will increase with increasing acetalization. This water sensitivity, which is sometimes undesirable, may be reduced by lowering the degree of acetalization. It can also be reduced by using polyvinyl alcohols which are not completely hydrolyzed. Particularly useful results have been obtained by using acetals wherein about 19% of the hydroxy groups of the polyvinyl alcohol are acetalyzed. This degree of acetalization has been found especially useful for the trimethyl-substituted acetals.

The anionic portion of the quaternary salt appears to have little to no effect on the ability of the acetals to function as mordants and may be selected from the various acid anions, e.g., sulfonates, etc. Especially useful results have been obtained using the toluenesulfonate salts.

In the aldehydes which are used to synthesize the acetals of this invention, the trialkylammonium substituent is preferably para to the aldehyde group. However, when desired, it should be understood that the metaand orthosubstituted compounds may be used. As examples of trialkylammonium benzaldehyde quaternary salts, mention may be made of p-trimethylammonium benzaldehyde p-toluenesulfonate, p-triethylammonium benzaldehyde ptoluenesulfonate, p-dimethylbutylammonium benzaldehyde p-toluenesulfonate, p-diethylbutylammonium benzaldehyde p-toluenesulfonate and p-methylethylbutylammonium benzaldehyde p-toluenesulfonate.

An acetal suitable for use in the image-receiving elements of this invention may be prepared, for example, by dissolving about 0.2 mole of polyvinyl alcohol in about 50 mls. of water and reacting it in the presence of about 0.03 cc. of concentrated sulfuric acid with about 0.033 mole of a trialkylammonium benzaldehyde quaternary salt for about 17 hours at 60 C. The polymer may be purified by making the above reaction mixture alkaline, using about 1.4 gms. of a 50% sodium hydroxide solution dissolved in mls. of water and dialyzing. The polymer may be isolated by freeze drying.

The following non-limiting example illustrates the preparation of a polymer for use in the image-receiving elements of the invention:

Example I 76 gms. (0.398 ml.) of p-(N-methyl-N-butylamino) benzaldehyde (prepared by processes described in Organic Syntheses, Volume 1, Gilman, page 208) were dissolved in 250 mls. of ether containing 75 gms. (0.405 ml.) of methyl p-toluenesulfonate. The mixture was heated at reflux overnight and then 4 hours at 100 C., upon removing the ether. The resulting p-butyldimethylamino benzaldehyde quaternary ammonium salt, (melting point 158 C.-160 C.), was crystallized from tetrahydrofuran and dried.

8.8 gms. (0.2 ml.) of Gelvatol 2-75 were dissolved in 50 mls. of water containing 37.7 gms. (0.1 ml.) of the dimethylbutylammonium benzaldehyde p-toluenesulfonate, prepared above. Fifteen drops of concentrated sulfuric acid in 10 mls. of water were added, and the mixture was heated at 60 C., under nitrogen overnight. Methanol was added to dissolve the reaction product. The polymer was isolated by precipitation into acetone and purified by reprecipitation from methanol into acetone and dried.

The novel image-receiving elements, Within the scope of this invention, may be prepared by coating a sheet of a suitable film support such as cellulose acetate, cellulose acetate-coated baryta paper, etc., which may be suitably subcoated for proper adhesion, with a solution, preferably a 3% to 10% solution, comprising the acetal. Usually the polymers are water soluble and can be coated from aqueous solutions. The coating and drying operations involved may be carried out by methods commonly employed in the art. The acetal polymers may comprise the sole dyeable film-forming material in the image-receiving layer, or it may be added to other image-receiving materials, e.g., gelatin, polyvinyl alcohol, N-methoxymethyl polyhexamethylene adipamide, etc. Especially useful results have been obtained when the acetals are used in combination with polyvinyl alcohol. When the acetal polymers of this invention are used in combination with other image-receiving materials, the ratio of the acetal polymer to the other image-receiving materials may be varied to suit particular needs. Especially good results have been obtained if the acetal polymers comprise 10% to 100% by weight of the film-forming materials.

The following nonlimiting examples illustrate the preparation of image-receiving elements within the scope of the invention:

Example 2 Example 3 A subcoated film support was coated with an aqueous coating solution comprising:

Percent Elvanol 72-60 2.4

p-Trimethylarnmonium benzaldehyde p-toluenesulfonate partial acetal 2.4 1-phenyl-S-mercaptotetrazole (dissolved in a 1 to 9 methanol water solution) 0.08 Sodium perborate 0.01 Boric acid 0.01

and a small amount of a nonionic wetting agent.

Example 4 A subcoated film support was coated with a coating solution comprising:

Example 5 A subcoated baryta paper was coated with a coating solution comprising:

cc. solution of Elvanol 7260 16 10% solution of the acetal as prepared in Example 1 (said 10% solution containing 3 cc. of glacial acetic acid per gram of the acetal) 4 10% solution of 1-phenyl-5-mercapto-tetrazole (solvent: methanol-water, 1 to 9 by volume) 0.4 Sodium tetraborate 0.5 Water containing a small amount of a nonionic wetting agent 25.5

A control for comparison with the above image-receiving sheets was prepared in the following manner:

Example 6 A subcoated film support was coated with a methanol- Water solution (1 to 9 by volume) comprising:

Percent Elvanol 7260 4.8 1-phenyl-5-mercaptotetrazole 0.08 Sodium perborate 0.01

and a drop of a nonionic wetting agent.

The image-receiving elements prepared in the above examples, along with the polyvinyl alcohol control, were tested in diffusion transfer processes by using them in processes employing multilayer photosensitive elements prepared in a manner similar to that disclosed in the abovementioned US. Patent No. 2,983,606. In general, the photosensitive elements comprised a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum; said emulsions having disposed in separate alkali-permeable layers behind them, respectively, a cyan dye developer, 21 magenta dye developer and a yellow dye developer. The particular dye developers employed in the photosensitive elements were (1) 1,4 bis [a methyl {3 (2,5' dihydroxyphenyl) ethylamino]-anthraquinone (a cyan dye developer), (2) 2- [p (2,5 dihydroxyphenethyl) phenylazo] 4 propoxy-l-naphthol (a magenta dye developer) and (3) 1- phenyl 3 N n hexyl carboxamido 4 [p (hydroquinonylethyl) -phenylazo] -5-pyrazolone (a yellow dye developer).

In conducting the test, areas of the photosensitive elements were exposed to (1) blue and green light only, (2) red and blue light only, (3) red and green light only, (4) totally exposed, and (5) subjected to no exposure. After the transfer process, the integral densities in each of these areas were measured by reflectance using red, green and blue filters.

The results, appearing in tabular form below, indicate the improved density obtained using the image elements of this invention,

POLYVINYL ALCOHOL CONTROL [Density] Exposure Red Green Blue Filter Filter Filter Blue and Green 1.18 0. 37 0. 41 Red and Blue. 0. 10 0.61 0. 40 Red and Green 0.07 0.19 0.88 Total Exposure 0. 04 0.11 0.11 No exposure 1. 22 1. 24 1. G5

IMAGE-RECEIVING ELEMENT OF EXAMPLE 2 [Density] Exposure Red Green Blue Filter Filter Filter Blue and Green 1. 65 0.80 0.55 0.33 1.00 0.71 0.19 0.27 1. 23 0.12 0.14 0.18 2. 22 2. 14 2. 45

IMAGE-RECEIVING ELEMENT OF EXAMPLE 3 [Density] Exposure Red Green Blue Filter Filter Filter Blue and Green 2. 0 0. 0.55 Red and Blue 0. 41 1. 06 0.67 Red and Green 0. 24 0.27 1. 21 Total Exposure 0.18 0.16 0.18 No Exposure 1. 9G 1. 2. 20

IMAGE-RECEIVING ELEMENT OF EXAMPLE 4 IMAGERECEIVING ELEMENT OF EXAMPLE 5 [Density] Exposure Red Green Blue Filter Filter Filter Blue and Green 1. 33 0.63 0. 55 Red and Blue 0. 10 1. 04 0.77 Red and Green 0.05 0. 18 1. 22 Total Exposure 0.07 0. 14 0.32 No Exposure 1.16 1.31 1. 58

The stability of the dye developers on the image-receiving elements of this invention was measured by dyeing (l) films comprising 90% polyvinyl alcohol and 10% of a p-trimethylammonium benzaldehyde quaternary salt partial acetal of polyvinyl alcohol; (2) films of polyvinyl alcohol; (3) films of gelatin, and (4) films of N-methoxymethyl polyhexamethylene adipamide with (a) 1,4-b1S-[ocmethyl B (2,5' dihydroxyphenyl) ethylamino] anthraquinone; (b) 2-[p-(2,5'-dihydroxyphenethyl)-phenylazo]-4-propoxy-1-naphthol, and (c) 1-phenyl-3-N-n-l1exyl carboxamido 4 [p (hydroquinonylethyl) phenylazo]-5-pyrazolone. The density of the films was measured and then the films were exposed to a battery of 250 watt sunlamps for periods up to 168 hours. The stability of the dye developers of the image-receiving elements of this invention was comparable to that on polyvinyl alcohol and superior to that on gelatin and N-methoxymethyl polyhexamethylene adipamide.

When the acetals are used in combination with other water-sensitive polymers, such, for example, as polyvinyl alcohol, it is preferable to also employ reagents such as hardeners, cross-linking agents, and other reagents which will reduce the water sensitivity of the resulting layer.

The image-receiving elements of this invention are especially useful in composite film units intended for use in a Polaroid Land camera, made by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of US. Patent No. 2,435,717, issued to Edwin H. Land on February 10, 1948. In general, such composite film units comprise a photosensitive element, an image-receiving element and a rupturable pod containing an aqueous alkaline processing solution. The elements and pod are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pod may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such rolls are well known to the art. See, for example, US. Patents Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

It is apparent that by selecting a film base from among suitable known opaque and transparent materials, refiec tion or transparent prints may be obtained.

It should be noted that other materials useful in the diffusion transfer processes may be incorporated into the image-receiving layer. As examples of such materials, mention may be made of dye mordants, anti-foggants, oxidizing agents, and acids and alkalies for pH adjustments.

Since certain changes may be made in the above products and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a process of forming a photographic image in color, wherein a latent image contained in an exposed silver halide emulsion is developed in the presence of an aqueous alkaline processing solution comprising a dye developer to provide an imagewise distribution of unoxidized dye developer and wherein at least a portion of said distribution of said unoxidized dye developer is transferred, by imbibition, to an image-receiving layer in superposed relationship with said photosensitive element to impart to said image-receiving layer a transfer image, the step of transferring said imagewise distribution of unoxidized dye developer to an image-receiving layer comprising a partial acetal of polyvinyl alcohol with a trialkylammonium benzaldehyde quaternary salt, the trialkyl substituents of said quaternary salt comprising together not more than 8 carbon atoms.

2. A process as defined in claim 1 wherein said trialkylammonium benzaldehyde quaternary salt is a para-trialkylammonium benzaldehyde quaternary salt.

3. A process as defined in claim 1 wherein about 19% of the hydroxy group of the polyvinyl alcohol is acetalyzed.

4. A process as defined in claim 1 wherein said partial acetal comprises 10 to by weight of the film-forming materials in said image-receiving layer.

5. A process as defined in claim 1 wherein said imagereceiving layer comprises polyvinyl alcohol in addition to said partial acetal.

6. A process as defined in claim 1 wherein said dye developer is an azo dye developer.

7. A process as defined in claim 1 wherein said dye developer is an anthraquinone dye developer.

References Cited by the Examiner UNITED STATES PATENTS 2,358,836 9/1944 Swan 26073 X 2,818,403 12/1957 Mochel et a1 26073 2,909,430 10/1959 Rogers. 2,983,606 5/1961 Rogers 9629 2,996,956 8/1961 Ryan et al. 2,997,390 8/1961 Land. 3,015,989 1/1962 Delangre et al. 88-65 FOREIGN PATENTS 804,971 11/1958 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

HAROLD N. BURSTEIN, PHILIP E. MANGAN,

Examiners. 

1. IN A PROCESS OF FORMING A PHOTOGRAPHIC IMAGE IN COLOR, WHEREIN A LATENT IMAGE CONTAINED IN AN EXPOSED SILVER HALIDE EMULSION IS DEVELOPED IN THE PRESENCE OF AN AQUEOUS ALKALINE KPROCESSING SOLUTION COMPRISING A DYE DEVELOPER TO PROVIDE AN IMAGEWISE DISTRIBUTION OF UNOXIDIZED DYE DEVELOPER AND WHEREIN AT LEAST A PORTION OF SAID DISTRIBUTION OF SAID UNOXIDIZED DY DEVELOPER IS TRANSFERRED, BY IMHIBITION, TO AN IMAGE-RECEIVING LAYER IN SUPERPOSED RELATIONSHIP WITH SAID JPHOTOSENSITIVE ELEMENT TO IMPART TO SAID IMAGE-RECEIVING LAYER A TRANSFER IMAGE, THE STEP OF TRANSFERRING SAID IMAGEWISE DISTRIBUTION OF UNOXIDIZED DYE DEVELOPER TO AN IMAGE-RECEIVING LAYER COMPRISING A PARTIAL ACETAL OF POLYVINYL ALCOHOL WITH A TRIALKYLAMMONIUM BENZALDEHYDE QUATERNARY SALT, THE TRIALKYL SUBSTITUENTS OF SAID QUATERNARY SALT COMPRISING TOGETHER NOT MORE THAN 8 CARBON ATOMS. 